Dynamoelectric machine



June 14, v1949. P. s. PoT'rs 2,473,259

DYNAMOELECTRIC MACHINE Filed Jan. 9, 1946 2 Sheet'S-Shee'c l Figi. /J

8 7 A 6 7 9 i s Inventor:

'Phil 3. Pot'bs,

His Attovney.

June 14, 1949. P. s. Pons 2,473,259

DYNAMOELECTRIC MACHINE I fg 'Wa/Lg Pig". -'Jjl" 60 [3-54 Inventor:

Phil Spotts,

bymm/mM/o Miu-1.4.1

i ww' U'Ni'rao srs'ras' PA'rsN'r orrlca NMM -cIlI-lccirlc Wayne.Ind.,a-lxnerto6en- Company, a eerporation of New lly invention relates to'dynamoelectric machine: and particuiarly to inductor eddy current t types of machines which are. adapted to be used as clutches. dynamometers. and brakes.

.An obiect of my invention is to provide an improved dynamoelectric machine of the'inductor.

type.

Another obiect of my invcntion is to provide an improved inductor type dynamoelectric machine whichisadaptedtoabsorbpowerandtobecooled by fluid supplied in direct contact with the eddy current surfaces thercof.

A further obiect of my inventiou is to provide an improved Wectric machine of' the inductor eddy current type in which a cooling fluid is supplied into direct contact with the eddy current surfaces of the machine and an arranxement is provided for minimizinx the collection of coolinx fluid in the end shields of the machine and directinx such coolinx fluid into drains. preferably in the lowermost slots of the statoxfrom which it is then exhausted.

Further objects and advantaxes of my invention will become apparent and my invention wili be better understood from the following description referrinx to the accompanyinx drawinx. and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forminx part of this speciflcation.

Inthedrawinx, Fix. i is a side elevational view. partly in section of a dynamoelectric machine. particularly adapted to be used as a dynamometer, which is provided with an embodiment of my improved construction; Fix. 2 is an enlarxed sectional view taken alonx line 2-2 of Fix. i; Fix. 3 is a fraxmentary sectional view taken alonx line l-I of Fix. 2; Fix. i is a plan view of the construction shown in Fix. 3; Fix. 5 is a perspective view of the end shield scoop shown in Fixs. i, 3, and 4; Fix. 8 is a side elevationai view. partly in section. of a dynamoelectric 'machine provided 2 Fixs. l to 5, inclusive, one embodiment of my invention applied to a dynamoelectric machine construction in which a machine of the.`eddy current indueto'r type is constructed to be used preferabiy as a dynamometer or a-brake. .In this construction. the dynamoelectric machine is provided with a stationary member having two core sections i and I of maxnetic material secured toxether -in any suitable manner. as by bolts 3, and

arranxed about an inner relatively rotatable member havinx a core 4 of magnetic material mounted on a shaft I rotatably supported by suitable antifriction ball bearinxs O arranxed in bearinx housinxs formed by sleeves 'I on the stationary member end shields I. The stationary member end shields 8 are adapted to support the stationary member core sections i and 2 for limited rotational movement by antifriction thrust roller bearinxs I mounted in suitable pedestais il. A suitable field excitinx windinx ii is mounted in a windinx recess i! formed in the stationary member between the core portions I and 2 for maxnetically excitinx the oores of the rotatable and stationary members of'the machine. A plurality of circumferentially spaced apart mountin'g screws it extends throuxhthe stationary member core into enxaxement with mountinx clips ll for position"- inx and centerinx the field excitinx windinx Il within the windinx recess il.

In this construction, enerxy is adapted to bc absorbed by the machine by the generation of eddy currents in the outer substantially smooth cylindricai surface of the rotatable member core 4 resuitinx from the periodic variation of the flux linhaxes of any xiven portion of the surface of slots lt formed therebetween to provide the dethe shaft I and the passaxe of these eddy currents v sired Variation in the iiux linkaxes mentionedv above. The eddy currents generated in the cylindrical surface of the rotatable member core l absorb the enerxy delivered to the machine by through the core l transforms this electrical enerxy into heat which must be dissipated. In order to remove this heat from the machine. coolinx fluid, such as water. is supplied to the air xap provided with another embodiment of my invenof the machine between the stationary and rotion; Fix. 10 is a sectional view taken alonx line it-ll of Fix. 9; and Fix. ii is a perspective view of an end shieid water scoop such as that shown in Fix. 9.

tatable member cores into direct heat transfer relationship with the surface of the rotatable member core l, and in this construction is suppiied throuxh a header i'l which connects with a Referrinxtotbe drawinxa'f have shcwnin sourceofcoolinxfluidsimpiythrouxnaiienble 3 hose liforminimiainstherestrainins eifectofthiseonnectiononlimitedrotationof the stationary member-of the machine. The. coolinznuidpassesfromthesuppiyheader |1 throuah suitabiepipcconnections laintopassasesllin the core of the stationary member into the windinz recess '|2 inback of the field exciting windins i I and fiows. around the windins i, thereby coolin: the windins, and then passes from this windins recess through h communication at the inner end thereof with the air :ap between the two relatively rotatable members and into heat transfer contact with -the outer peripheral surface of the rotatable member core l, from which it flows .longitudinally towards both ends of the machine.

This coolinz iiuid absorbs the heat from the outer cylindrical surface of the core l, and it is desirable that this coolina fluid should be removed from the surface of the core l when it has absorbed a desired amount of heat to prevent overheating of the machine and also to minimize hydraulic drag thereof which might result if the entire air gap should become iilled with water. This removal of the heated coolins fluid is facilitated by the provision of lonsitudinally extendinz 'scoop members of nonmagnetic material extending outwardly towards the smooth cylindrical surface of the core l of the rotatable member and into adjacent slots ll-in the lowermost part of by forming outer lonzitudinal edses 22 which scrape or scoop fluid from the outer surface of the rotatable member core 2 as it rotates and directs the removed coolinz fluid into the stator slots ll. This removed cooling fluid is adapted to be drained from the machine, through suitable drain passaaes 22 which extend through the stationary member core and communicate with drain connections 22 which are connected to any suitable cooling fluid drains. In this construction, the cooling iiuid is assisted in its now into the lowermost slots II and the drain passages 22 by the provision of lonsitudinally extending transversely curved substantially smooth guiding surl'face members 2| of nonmagnetic material arranged in the slots II on the trailing sides of the teeth'adJacent each of the scoop members 2| for guiding cooling fluid from the air gap into the slots lt and the drain passases 22 for either direction of rotation of the rotatable member. The outer surface of these guiding members 25 is transversely curved to. provide a curved outer slot surface extending from the air gap and of the tooth into the base of the slot. If only one set of these scoops and guiding surface members is provided, it is desirable that a tooth I! should be the lowermost portion of the stationary member core in order to provide at least one scoop and one guiding surface member on each side of the lowermost tooth to provide for the scooping of lcooling fluid from the rotatable member surface for either direction of rotation thereof. Bailies 22 are provided for closing oif the lower slot ends adjacent the field exciting winding recess |2 to assure that the scooped off fluid flows out through the drain passages 22 rather than in the space around the fleld exciting winding ll. This longitudinal air gap scoop arrangement is not my invention but is the invention of Roland F. Hertel and is described and claimed in his copending application, Serial No. 638,374, filed December 29, 1945, now Patent Number 2.460,749, and assined to the assignee of this application. With this construction, it has been found that the hydraulic zradient of the coolins duid on thev cylindrical surface of the rotatable member core l causes a certain amount of the coolina fluid to flow. axially o! both ends of the coolinz member core into the space between the cores of the mal chine and the end shieids 2 and to collect in this end shield space and rotate with the rotatable member'without iiowin: directly out of the drain at the lowermost part of the machine, thereby causing a considerable amount of hydraulic drag which may produce erratic results in the measurement'of the torque on the machine. I have found that the provision of end shield scoops 21 formed with inwardly and downwardly curved side surfaces 22 which provide scoops that are wider at the top than at the bottom and arranzed in the lowermost part of the'end shields 2 substantiallyopposite the tooth ll provided with the slot scoops 2| provides for minimizins the turning of the cooling fluid with the rotatable members and for the drainase of this cooling fiuid out of the end shield spas and into the drains 21 from which it is removed from the machine. These end shield scoops 21 are preferably secured to the end shields 2 in any suitable manner, as by bolts 29, and formed' with inner ends 22 which substantially conform in contours and dimensions to the ends of slot scoops 2|. together with the tooth i! on which the scoops 2| are mounted. The rate of flow of the coolinz iiuid may be regulated as desired responsive to various characteristics of the machine, such as the amount of cooling fluid which may adhere to the ,cylindrical surface of the rotatable member l or in accordance with the rate at which the cooiinc fluid may be removed from the machine or with the temperature of the exhausted cooling fluid or any other desired characteristic as is conventionally incorporated in the cooling systems of this typa of machine.

In Figs. 6, '1, and 8, I have shown another embodiment of my invention applied to' a dynamoelectric machine which is preferably adapted to be used as a dynamometer or a brake in which the stationary member of the machine is made of two core sections 2| and 22 secured together by any suitable means such as bolts 22 arranged in circumferentially spaced relation and provided with a plurality of longitudinally extending circumferentially spaoed teeth 24 in the inner peripheral air gap surface of the stationary member core sections 2| and 22. Substantially all of the slots 25 formed between the stationary member core teeth 2| are filled with nonmagnetic material 22 in order to provide a substantially smooth cylindrical peripheral air sap surface to this member of the machine. A rotatable member is provided which is adapted to react electrodynamically with the stationary member of the machine and includes a core 21 of magnetic material having a substantially smooth cylindrical peripherai surface spaoed from the inner peripheral surface of the stationary member core by a small air sap. This core 21 is mounted on a shaft 22 which is rotatably supported by antifriction ball bearings 22 mounted in a bearing housing formed by sleeves ll which extend from stationary member end shields ll. These stationary member end shields 4| are secured to the stationary member core sections and are rotatably supported by antifriction thrust roller bearings 42 suitably mounted in pedestals 43 which support the relatively stationary mem-l ber of the machine for a limited amount of rotational movement, such that the torque thereon may be transmitted through suitable torque arms Sim lltoanysuitableforoemeasuringdevieell. 'I'he cores of the rotatable and stationary members of the machine are magnetically excited by a' suitableiieldexcinlwindingwhichismounted in a winding recess ll formed between the two parts of the stationary member core. lnergisationoftheileldexcitingwindingwhentherotatable member I'l is rotated causes eddy 'currents -to be generated in the air gap surface of the rotatable member core due to thegflux variations as this surface of the rotatable member core the stationary member core teeth ll. and these eddy currents absorb energy which is transmitted to the machine through the shaft ll and transform this energy into heat which raises the temperature of the machine. In order to dissipate this heat energy. cooling fluid is admitted into the machine through a cooling fiuid header I'l which may be connected to a suitable source of cooling fluid supply, such as a source of water, by a ilexible hose I. which will minimine the restraint on the rotation of the stationary' member by this connection in the same manner as the construction shown in Fig. l. As in Fig. 1, the water passes from the water header i'l through connecting Dipes I! and through the stationary member cores into the winding recess I .l'l around the fleld exciting winding lt and from a communication of this winding reoess with the air gap into the air gap and ilows towar-ds both ends of the machine. In'this construction, no provision is made for scooping the cooling fluid from the surface of the rotatable member core Il, and all of the cooling fiuid passes 'axially into the end shield space at both ends of the machine. It has been found that this cooling fluid tends to rotate with the rotatable member and may provide an undesirable drag and erratic action of the machine. In order to eliminate these undesirable features, I provide end shield scoops 48 which are preferably mounted directly on the end shields ll 'by suitable bolts 49 and are formed with downwardly and outwardly curved tapered side surfaces 50 which are arranged to direct the cooling fiuid from the end shield space into drain passages Ii formed in at .least one of the lowermost slots of the machine through the non-magnetictflller material in such slots. The cooling fiuid is adapted to pass from the drain passages 5| into drain openings I! formed through the stationary member cores 3| and 32 from which it empties into drain connections II and passes into suitable drains Il which are constructed so as to minimize restraint on the rotation of the stationary member of the machine. With this construction, the water pases from the rotatable' member surface into the end shield space and is redirected as it reaches the lower portion of the end shield, from which it drains outwardly, as explained above, without producing any appreciablesdrag on the machine.

In Figs. 9, 10, and ll, I have shown another embodiment of my invention, in which the stationary and rotatable members of the machine are formed substantially the same as those shown in Fig. 1 in which the stationary member is provided with a core of magnetic material having members I and 2. as shown in Fig. l, and the rotatable member is formed with a core I of magnetic material which is mounted on a shaft 5 suitably supported in bearinss which may be made similar to those shown in Figs. l and 6. Magnetic excitation of the machine is provided by a field exciting winding ii arranged in a winding recess II and the stationary member is nally in the lowermost slot or slots of the machine similar to the construction disclosed and claimed in co-pending application. Serial No. 638,374, nled December 29, 1945, now Patent Number 2360349, by R. F. Hertel, and assigned to the assignee of this application. These slot scoops do not form a part of this invention and may be omitted from the construction if desired. In the arrangement shown specifically in Figs. 9 and 10, these slot scoops have not been included. In this machine, the cooling fluid is adapted to be supplied as in the construction shown in Fig. 1 in order to cool the field exciting winding li and then passes into heat transfer contact with the outer peripheral surface of the rotatable member core 4 and longitudinally into the spaces within the end shields 8 of the machine. As in the other construction, this cooling fiuid will tend to rotate with the rotatable member core l and may produce undesirable drag and erratic action of the machine. In order to eliminate or minimize these eflects, I provide'end shield scoops which are preferably mounted in the end shields I of the machine in any suitable manner, as by bolts 58. These end shield scoops are formed with downwardly curved side surfaces 51 which are adapted to stopthe rotation of the cooling fluid in the end shield and to redirect this cooling fluid into drain passages 58 formed through the end shields 8 and into drain connections 59 which may extend into the enlarged ends of a suitable drain 60 which permts a limited amount of rotational movement of the drain connection 59 without interference of the drain'with such movement of the stationary member of the machine. As in the construction shown in Fig. l, bailles 26 are arranged on the inner winding recess end of the slot IG in order to minimize the passage of cooling fiuid through the slot |6 into the winding recess. These bai'fles 26 preferably extend only for a small distance on both sides of the lowermost part of the machine, as water will not interfere greatly with the operation of the machine .if it passes into these slots above the lowermost portion of the machine, and these baiiles 28 function principally to minimize the passage of the heated water through the slots IS into the recess |2 due to the collecting action of the end shield scoops 55.

While I have illustrated and described particular embodiments of my invention, modifications thereof will occur to those skilled in the art. I desire it to be understood, therefore, that my invention is not to be limited to the particular arrangements disclosed, and I intend in the appended claims to cover all mcdifications which do not depart from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A dynamoelectric machine having a relatively stationary member with a corehof magnetic material and a relatively rotatable member with a core of magnetic material arranged with an air gap between said cores, means including a field exciting winding for magnetically exciting said cores. longitudinally extending teeth with slots therebetween in the inner peripheral surface of the magnetic material of said stationary member core, means for supplyig lcooling fluid into said air gap onto said rotatable member for passage to the ends of the machine. means inamen cludingl I an end shield on each end of said stationary member for substantially preventing pas- 'sage of cooling iiuid out of the ends of the machine, means including drain passages for draining cooling fluid from the lower part of said mat chine, and means including a fluid scoop member with a core of magnetic material having a relatively smooth substantially cylindrical outer surface arranged with an air gap between said cores, means including a field exciting winding for magnetically exciting said cores, longitudinally extending teeth with slots therebetween in the inner peripheral surface of the magnetic material of said stationary member core, means for supplying cooling fluid into said air gap onto said cylindrical surface of said rotatable member, means including an end shield on each end of said stationary member for substantially preventing passage of cooling fluid out of the ends of the machine, means including a fiui'd scoop member having sides wider adjacent said end shield than adiacent said stationary member core and arranged in spaces between each of said end shields and said stationary member core opposite one of said teeth in the lower part of said machine on each end thereof for guiding cooling fluid from said end shield into one of said slots, and means including drain passages extending into communication with -said slots .for draining cooling fluid therefrom;

3. A dynamoelectric machine having a relatively stationary member with a core of magnetic material and a relatively rotatabie member. with a core of magnetic material having a relatively smooth substantially cylindrical outer surface arranged with an air gap between said cores, means including a field exciting winding for magnetically exciting said cores, longitudinally extending teeth with slots therebetween in the inner peripheral surface of the magnetic material of said stationary member core, means for sunplying cooling fluid into said air gap onto Said cylindrical surface of said rotatable member, means including an end shield on each endv of said stationary member for substantialiy preventing passage of cooling fluid out of the ends of the machine, means including a. fluid scoop member having sides wider adjacent said end shield than adjacent said stationary member coreand arranged in spaces between each of said end shields and said stationary member core opposite substantially the center of one of said slots in the lower part of said machine on each end thereof for guiding cooling fluid from said end shield into said latter slots, and means including drain passages extending into communication with said slots for draining cooling fluid therefrom.

4. A dynamoelectric machine having a relatively stationary member with a core of magnetic material ,and a relatively rotatable member with a core of magnetic material having a relatively smooth substantialiy cylindrical outer surface arranged with an air gap between said cores, means including a field exciting winding for magnetically exciting said cores, longitudinally extending teeth with slots therebetween in the inner peripheralsurfaceofthemagneticmateriaiofsaid stationary member core, tic means for substantially niling said slots providins a substantially smooth cylindrical surface to said toothed core, means for supplying cooling fluid for passage around said field exciting winding and into said air gap onto said cylindrical surface of said rotatable member, means including an end shield on each end of said stationary member, means including a fluid scoop member arranged in each of said end-shields adiacent an end of one of said slots in the lower part of said machine on each end thereof for guiding cooling fluid from said end shield into passages insaid slot filling means in said latter slots, and means including drain passages extending into communication `with said latter slots for drainmz cooung mna i therefrom.

IS.A A dynamoelectric machine having a relatively stationary member with a core of magnetic material and a relatively rotatable member with a core of magnetic material arranged with an air gap between said cores, means including a field exciting winding for magnetically exciting said cores, longitudinally extending teeth with slots therebetween in the inner peripheral surface of the magnetic material of said stationary member core, means for supplyins cooling fluid into said .air gap onto said rotatable member, means including an end shield on each end of said stationary member forlsubstsntially preventing passage of cooling fluid out of the ends of the machine, means including a fluid scoop member having curved sides wider at the top than at the base and arranged in spaces between each of said end shields and said stationary member core and substantially at the height of said teeth and each arranged opposite substantialiy the center of one of said slots in the lower part of' said machine on each end thereof for luiding cooling fluid from said end shield into said latter slots, and means including drain passages extending into communication with said slots for draining cooling fluid therefrom.

6. A dynamoelectric machine having a relatively stationary member with o. core of magnetic material and a relatively rotatable member with a core of magnetic material having a relatively smooth substantially cylindrical outer surface arranged with an air gap between said cores, means including a field exciting winding for magnetically exciting said cores, longitudinally extending teeth with slots therebetween in the inner peripheral surface of the magnetic material of said statiorfary member core, nonmagnetic means for substantially iilling said slots providing a substantially smooth cylindrical surface to said toothed core, means for supplyins cooling nuid into said air gap onto said cylindrical surface of said rotatable member, means including an end shield on each end of said stationary member, means including a fluid scoop member arranged in spaces between each of said end shields and said stationary member core opposite substantially the center of one of said slots in the lower part of said machine on each end thereof for guiding cooling fluid from said end shield into passages in said slot lling means in said latter slots, and means including drain passages extending into communication with said latter slots for draining cooling fluid therefrom.

7. A dynamoelectric machine having a relatively stationary member with a core of magnetic material and a relatively rotatable memberwithacoreofmagneticmaterialwithan airgapbetweensaidcoreameansformagnetically exciting said, cores, longitudinaily extending teeth with slots therebetween in the inner Deripheral surface of the magnetic material of said staticnary member core. means for supplying cooling fluid into said air gap onto said surface of said rotatable member, means including longitudinally extending slot scoop members of nonmagnetic material mounted in slots in the lower part of said stationary member and having curved sides with outer iongitudinal edges extendingtowards the adiacent teeth for removal of excess fluid from said rotatable member core air sap surface and for directing suchf removed coolins 'nuid into said latter slots, an end shleld on each end of said stationary member. means including a fluid scoop member on each end of said machine having sides curved downwardly wider at the top than vat the base and outwardly wider adiacent said end shields than said core and arranged in spaces between the lower part of said end shields and said stationary member core and adiacent the ends of said slot scoop members in the lower part of said machine for guiding cooling fluid from said end shields into said latter slots, and means for draining cooling fluid from said latter slots.

8. A dynamoelectric machine having a relatively stationary member with .a core of magnetic material and a relatively rotatable member with a core of magnetic material with an air gap between said cores, means for magneticaliy exciting said cores, longitudinally extending teeth with slots therebetween in the inner peripheral surface of the magnetic material of said stationary member core, means for supplying cooling fluid into said air gap onto said surface of said rotatable member, means including at least one longitudinally extending slot scoop member of nonmagnetic material mounted in a slot in the lower part of said stationary member and having la curved side with an outer longitudinal edge extending towards the adjacent tooth for removal of excess fluid from said rotatable member core air gap surface and for directing such removed cooling fluid into said latter slot, an end shield on each end of said stationary member, means including a fluid scoop member on each end of said machine having curved sides wider at the top than at the base and arranged in spaces between the lower part of said end shields and said stationary member' core and adiacent the ends of said slot scoop member in the lower part of said machine for guiding cooling fluid from said end shields into said latter slot, and means for draining cooling fluid from said latter slot.

9. A dynamoelectric machine having a relatively stationary member with a core of magnetic material and a relatively rotatable member with a core of magnetic material with an air gap between said cores, means for magnetically exciting said cores, longitudinally extending teethwith slots therebetween in the inner peripheral/ surface of the magnetic material of said stationary member core, means for supplying cooling fluid into said air sap onto said rotatable member, means including at least one longitudinally extending slot scoop member of nonmagnetic material mounted in a slot on each side of said machine adiacent the lower part of said stationary member and having curved sides with outer iongitudinal edges extending towar the adiacent teeth and a narrower base section mmam! o: aula :mm ma ni' gsp.

and for directing such removed coolina fluid into said latter slot, means including an endshield on each end of said stationary member for substantially preventing passage of cooling .nuid out of the ends of the machine, means in-A cluding a fluid scoop member on each end of ber core and arranged in spaces between said end shields and said stationary member core and extending from said slotscoop member in the lower part of said machine for guiding cooling fluid from said end shields into said latter slot. and means for draining cooling fluid from said latter slot.

10. A dynamoelectric machine having a relatively stationary outer member with a core of magnetic material and a relatively rotatable inner member with a core of magnetic material having a relatively smooth substantially cylindrical outer surface arranged with an air gap between said cores, means including a field exciting winding for magnetically exciting said cores, means for rotatably supporting said rotatable inner member, means for rotatably supporting said outer member. means for measuring the torque on said outer member, longitudinally extending teeth with slots therebetween i in the inner peripheral surface of the magnetic material of said outer member core, means for supplying cooling fluid into said air gap onto said smooth cylindrical surface of said rotatable inner member, means including an enclosing end shield on each end of said stationary member for substantially preventing passage of cooling fluid out of the ends of the machine, means including a fluid scoop member having curved sides wider at the top than at the base and wider adjacent said end shield than adjacent said stationary member core and arranged in spaces between said end shields and said stationary member core and substantially the height of said teeth and arranged opposite one of said slots in the lowermost part of said machine for guiding cooling fluid from said end Shield into said latter slot, and means including a drain passage extending into communication with said latter slot for draining cooling fluid therefrom.

ll. A dynamoelectric machine having a relatively stationary outer member with a core of magnetic material and a relatively rotatable inner member with a core of magnetic material having a relatively smooth substantially cylindrical outer surface arranged with an air gap between said cores, means including a field exciting winding for magnetically exciting said cores, means for rotatably supporting said inner member, means for rotatably supporting said outer member. means for measuring the torque on said outer member, longitudinally extending teeth 'with slots therebetween in the inner peripheral surface of the magnetic material of said outer member core,'m'eans for supvplying cooling fluid into said airV gap onto said smooth cylindrical surface of said rotatable inner member, means including at least one longitudinally extending slot scoop member of nonmagnetic material mounted in a slot on each side 'of said machine adjacentthe lowermost part o'f said outer member and having curved sldes with outer longitudinal edges extending towards the 'adjacen't teeth and with a narrower base section for removal of excess fluid from said rotatable ventin W of cooiinz iiuid out ot the ot the machine, means including o iiuld xnembex` on each side o! said machine cmvedaideewidernttbetopthannttbebue and vider ndjecent said end shield cent id stntionnry member core and nn'nnzed in space: between said end shields and said atetionnry membex` core substantinlly the heizht of snidteethnndextendinziromsaidslotacoop member in the lowermost port of said machine UNITED B'I'A'I'H PATNTS 

